Use of SPECT/CT for improved sentinel lymph node localization in endometrial cancer.

OBJECTIVE: To assess the usefulness of adding SPECT/CT to planar images for pre-surgical sentinel lymph node (SLN) identification in endometrial cancer (EC), a technique that could have an important clinical impact on the staging, treatment, and prognosis of EC patients. METHODS: We compared the planar and SPECT/CT lymphoscintigraphic images of 44 patients with high-risk EC who underwent sentinel lymph node procedure (SLN) using an injection technique recently developed at our center known as TUMIR (Transvaginal Ultrasound Myometrial Injection of Radiotracer). 148 MBq (4 mCi) of 99mTc-nanocolloid were injected, guided by transvaginal ultrasound imaging. Planar and SPECT/CT images were performed in all 44 patients. RESULTS: SLNs were seen on planar images in 32 cases (73%) and in 34 cases (77%) using SPECT/CT. A total of 88 SLNs were depicted by planar lymphoscintigraphy while SPECT/CT visualized a total of 110 SLNs. SPECT/CT changed the assessment of the SLNs visualized in planar lymphoscintigraphy in 26 cases, either by modifying the number and/or the location of the SLNs detected. External iliac chain was the most frequent location of SLN detection (71%) in the 34 cases. Fifteen of these patients (44%) showed para-aortic SLNs. One case had exclusive para-aortic drainage (3%) that was only visualized by SPECT/CT. In another case, SPECT/CT was able to localize the only pelvic metastatic lymph node not visualized by planar images. CONCLUSIONS: SPECT/CT combined with planar imaging improves preoperative SLN detection and provides valuable anatomic information that enhances the presurgical stage of the SLN technique in endometrial cancer.